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        <title>类-Species允许覆盖默认的构造函数</title>
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        <h1>类-Species允许覆盖默认的构造函数</h1>
        <p>来源:<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Classes">https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Classes</a></p>
        <script>
            class MyArray extends Array {
              // Overwrite species to the parent Array constructor
              static get [Symbol.species]() { return Array; }
            }
            var a = new MyArray(1,2,3);
            var mapped = a.map(x => x * x);
            console.log('mapped='+mapped);
            console.log(mapped instanceof MyArray); 
            // false
            console.log(mapped instanceof Array);   
            // true
        </script>
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